1. Field
The embodiments herein relate generally to composite structures and more particularly to a protocol for development of process parameters for double vacuum debulk processing of composite prepreg for original parts manufacturing and specific application to a carbon-epoxy pre-impregnated laminate (pre-preg) system for non-autoclave processing.
2. Related Art
Double vacuum bag processing, aka double vacuum debulk (DVD) processing, may be employed to cure composite parts such as prepreg laminates. DVD processing provides flexibility in parts processing and is not limited by the size of the part. The DVD process is also less capital equipment intensive than autoclave processing, and may provide tighter dimensional control and higher mechanical performance in the cured part compared to autoclave processing or single vacuum bag (SVB) processing.
Manufacturing processes and procedures for prepreg tape materials, specifically toughened carbon/epoxy prepreg, have vacuum bag process limitations that cause excessively long processing times. A standard vacuum bag and curing processes used in the prior art results in a patch or laminate that may have excessive porosity levels. Typical acceptable porosity levels are ≦2% for original manufacturing.
Additionally, building the laminate thickness in stages with adhesive layers in between is very time consuming and can have undesirable affects as having multiple layers of adhesive imbedded into the laminated part may result in excessive porosity in the adhesive layers. This result may be problematic for thick laminates as the required strengths may not be able to be obtained using the current vacuum bag processes. Unless the part can be processed in an autoclave, a thick toughened carbon/epoxy composite may not be possible with prior art techniques.
It is therefore desirable to provide a protocol for establishing process times and parameters for application to a standard DVB debulk and curing approach. It is further desirable to employ the developed protocol for specific process parameter definition for composite laminate creation in toughened carbon/epoxy prepreg materials.